Returns values along a linear trend. Fits a straight line (using the method of least squares) to the arrays known_y's and known_x's. Returns the y-values along that line for the array of new_x's that you specify.
Syntax
TREND(known_y's,known_x's,new_x's,const)
Known_y's is the set of y-values you already know in the relationship y = mx + b.
If the array known_y's is in a single column, then each column of known_x's is interpreted as a separate variable.
If the array known_y's is in a single row, then each row of known_x's is interpreted as a separate variable.
Known_x's is an optional set of x-values that you may already know in the relationship y = mx + b.
The array known_x's can include one or more sets of variables. If only one variable is used, known_y's and known_x's can be ranges of any shape, as long as they have equal dimensions. If more than one variable is used, known_y's must be a vector (that is, a range with a height of one row or a width of one column).
If known_x's is omitted, it is assumed to be the array {1,2,3,...} that is the same size as known_y's.
New_x's are new x-values for which you want TREND to return corresponding y-values.
New_x's must include a column (or row) for each independent variable, just as known_x's does. So, if known_y's is in a single column, known_x's and new_x's must have the same number of columns. If known_y's is in a single row, known_x's and new_x's must have the same number of rows.
If you omit new_x's, it is assumed to be the same as known_x's.
If you omit both known_x's and new_x's, they are assumed to be the array {1,2,3,...} that is the same size as known_y's.
Const is a logical value specifying whether to force the constant b to equal 0.
If const is TRUE or omitted, b is calculated normally.
If const is FALSE, b is set equal to 0 (zero), and the m-values are adjusted so that y = mx.
Remarks
Example
The example may be easier to understand if you copy it to a blank worksheet.
Selecting an example from Help
The first formula shows corresponding values to the known values. The second formula predicts the next months values, if the linear trend continues.
|
|
Note The formula in the example must be entered as an array formula. After copying the example to a blank worksheet, select the range C2:C13 or B15:B19 starting with the formula cell. Press F2, and then press CTRL+SHIFT+ENTER. If the formula is not entered as an array formula, the single results are 133953.3333 and 146171.5152.